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Synfacts 2014; 10(1): 0057
DOI: 10.1055/s-0033-1340438
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Pd-Catalyzed Asymmetric Ring Opening of Azabenzonorbornadienes

Contributor(s):
Hisashi Yamamoto
,
Sukalyan Bhadra
Huang K.-L, Guo C, Cheng L.-J, Xie L.-G, Zhou Q.-L, Xu X.-H, * Zhu S.-F. * Nankai University, Tianjin, P. R. of China
Enantioselective Palladium-Catalyzed Ring-Opening Reaction of Azabenzonorbornadienes with Methyl 2-Iodobenzoate: An Efficient Access to cis-Dihydrobenzo[c]phenanthridinones.

Adv. Synth. Catal. 2013;
355: 2833-2838
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Publication History

Publication Date:
13 December 2013 (online)

 
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Key words

asymmetric ring opening - azabenzonorbornadienes - chiral spiro ligands - palladium

Significance

In the presence of electron-rich chiral spirophosphine ligands, I2 as key additive, and zinc powder as reducing agent, Pd(MeCN)2Cl2 efficiently catalyzes the ring opening of azabenzonorbornadiene with various 2-iodobenzoates. The resulting enantioenriched cis-dihydrobenzo[c]phenanthridinones serve as core structure of numerous optically active natural products.


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Comment

The use of easily available organic halides instead of organometallic reagents and the construction of fused ring systems with multiple stereocenters via the tandem asymmetric ring-opening–cyclization process make the strategy remarkably efficient. A direct application of the present methodology was demonstrated via the concise total synthesis of (+)-chelidonine.


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